Stack changing device

ABSTRACT

A remaining-stack carrying device ( 3 ) in a sheet feeder ( 2 ) is used in non-stop stack changing. The remaining-stack carrying device ( 3 ) is integrated into the stack feeder ( 2 ) to simplify retrofitting. A remaining-stack lifting gear ( 5 ) uses the lifting elements present in each sheet feeder ( 2 ) for lifting and lowering during stack exchange.

FIELD OF THE INVENTION

The present invention relates to sheet-fed printing machines and, moreparticularly to an improved stack changing device for sheet feeders ofsheet-fed printing machines.

BACKGROUND OF THE INVENTION

It is a known practice, in sheet feeders of sheet printing machines orother sheet-processing machines to provide arrangements for automatedstack changing. These can consist of rack-type structures, so-calledremaining-stack carrying devices, which are provided with thrusting andlifting drives for horizontal and vertical movement. Such so-callednonstop stack changers are suited for example during the printing ofpaper sheets, i.e. in machine running, to remove remainders ofworked-out sheet stacks from a pallet provided, for example, withgrooves and to deposit them again on a new sheet stack subsequentlyinstalled into the sheet feeder. Known devices are marked by highconstruction and assembly expenditures, and require specialconstructions of the sheet feeders. Further, devices are used in whichthe remaining-stack carrying device(s) have a rack engaging into thegrooves of the pallet. This rack has to be removed when theremaining-stack is joined with the newly installed sheet stack to form awhole stack comprising the two stack parts. This involves high drivingforces, and very severely strains the sheets of the stack lying next tothe section point. Furthermore, restraining means have to be providedthat prevent a shifting of the stack parts, and in so doing severelystrain the stack edges. Furthermore, the operation of the sheet feederitself is severely hampered or even rendered impossible. The sheetflowis difficult to control during the changing process, so that again andagain waste sheets result.

Devices have already been developed that partly avoid some of thedisadvantages described. Thus, from DE 3931710 C2 there is known anonstop sheet feeder for rotary sheet-fed printing machines. It has aremaining-stack carrying device which is arranged underneath a conveyortable. The remaining-stack carrying device has a closed frame on whichnonstop rods are arranged, which can be driven as piston rods ofindividual cylinders by means of a pressure medium, and which aredrivable into grooves of a pallet carrying a sheet stack. The nonstoprods lie in the driven-in state on both sides of the frame and are to beremoved successively from the area of the sheet feeder. Nothing is saidabout the sequence of operation. The bridging of the gap conditioned bythe nonstop rods between main stack and remaining-stack constitutes, inthe stack unification, an obstacle to a faultless continuous process.The device is not usable, since the sheet stack must be tilted.

From DE 4203500 A1 a sheet feeder is known. It has parallel to the sheetfeeder and allocated to the sheet feeder on the face side, an auxiliarystack carrying device as an independent component. With this device,over a common drive, there are provided individually drivable pointedbars which are drivable into grooves of a pallet carrying a sheet stack.The drive has individual chain drives which are coupleable onto therespective pointed bars. For guiding and accessing the chain drives,special constructive measures are required. The chain drives completelyblock the space in front of the sheet feeder, so that the latter is notaccessible. In the stack changing, the pointed bars are removed from thestack zone, in the joining of main stack and remaining-stack, first onthe outside, then in the middle, and last in the zone between thealready pulled pointed bars, so that there is supposed to result agentle depositing of the remaining-stack on the sheet stack. This,however, is possible with the requisite precision only in the case ofheavy materials, such as sheets of metal, since the sheets arch indifferent directions and must descend over a large gap that is formed bythe pointed bars.

Further, from DAS 1095297 a sheet carrier with several stack-liftingmechanisms is known. It has a fork-shaped remaining-stack carryingdevice, which is provided with remaining-stack bars slidable intogrooves of a pallet. The device makes possible the taking over of aremainder of a sheet stack from the pallet for the continuous in-feed ofthe sheets while a new sheet stack is installed into the sheet feeder.The remaining-stack is connected with a separate lifting mechanismparallel to the main stack lifting mechanism inside the sheet feeder, sothat the remaining-stack is continuously liftable. The operating rangeof the remaining-stack carrying device is restricted. Theremaining-stack carrying device hampers access of the sheet feeder.

OBJECTS AND SUMMARY OF THE INVENTION

In view of the foregoing, an object of the present invention is toprovide an improved stack changing device which overcomes the problemsassociated with prior art designs.

A more specific object of the present invention is to provide a stackchanging device which can be easily integrated into a sheet feeder.

The present invention provides these and other advantages and overcomesthe drawbacks of the prior art by providing a stack changing devicewhich utilizes an improved apparatus for receiving a remaining-stack andtransferring the remaining stack to a newly fed-in sheet stack.

It is advantageous that carrying bars movable independently from oneanother are provided in the device, which for the unburdening of thesheet material are pulled out of the stacking zone not simultaneously,but offset from one another. The drive forces are thereby kept low andthe cost of the drives of the remaining-stack bars is reduced. Thedevice can be used, therefore, instead of a manual nonstop arrangementon a sheet feeder, and also be reequipped without the need for expensiveconstructive measures and large space requirements.

These and other features and advantages of the invention will be morereadily apparent upon reading the following description of preferredexemplary embodiments of the invention and upon reference to thedrawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of an illustrative embodiment of a sheetfeeder constructed in accordance with the present invention.

FIG. 2 is a plan view of a sheet feeder; and

FIGS. 3-5 are schematic side views of the sheet feeder of FIG. 1 showingthe operation of the stack changing device.

While the invention will be described and disclosed in connection withcertain preferred embodiments and procedures, it is not intended tolimit the invention to those embodiments. Rather it is intended to coverall such alternative embodiments and modifications as fall within thespirit and scope of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In FIG. 1 a sheet feeder 2 is represented joined with a sheet processingmachine, for example with a sheet printing machine 1. In the sheetfeeder 2 there is installed a sheet stack S for processing. The sheetstack S can be lifted by means of a main stack lifting mechanism, whichis not shown in detail here, in the rhythm of the sheet processing. Thesheets of the sheet stack S are singled on its upper side and fed to thesheet printing machine 1 in a sheet stream. In the sheet feeder 2 thereis provided, for this purpose, a sheet singling arrangement 4. In thesheet feeder 2 there is arranged, further, a remaining-stack carryingdevice 3 which is assigned to the face side of the sheet feeder 2 turnedaway from the sheet printing machine 1.

The remaining-stack carrying device 3 is provided with a frame, in whichthere are borne, longitudinally shiftably, remaining-stack bars 7. Bymeans of the frame 6 the remaining-stack carrying device 3 is suspendedon a remaining-stack lifting mechanism 5. The remaining-stack liftingmechanism 5, here, is shown only in its position, but not in details.The remaining-stack lifting mechanism 5 serves to hold a remaining-stackin the sheet feeder 2, and to lift it in the rhythm of the sheetprocessing. For this reason the remaining-stack lifting mechanism 5 isalso controllable synchronously with the main-stack lifting mechanism.The remaining-stack lifting mechanism consists of vertical guide rails 8connected with the sheet feeder 2, on which (rails) the frame 6 isguided, and it has, for example, lifting chains by means of which theremaining-stack carrying device 3 is raisable or lowerable.

In FIG. 2 the sheet feeder 2 is shown in a top view. Upon the sheetfeeder 2 there follows in the sheet running direction, indicated by anarrow, a so-called conveyor table 20, over which the sheet streamgenerated by the singling is transported to the sheet-processingmachine, for example to the printing machine 1. The orientation of theremaining-stack bars 7 is represented in their arrangement with respectto the sheet feeder 2, only the two outer remaining-stack bars 7 beingshown, while others are indicated with action lines. The position shownis, for example, the readiness position before the onset of a changingprocess, or the waiting position outside of the servicing zone of thesheet feeder 2. The remaining-stack bars 7 are guided there inside theremaining-stack carrying device 3, so that in the position shown theyoccupy a horizontal placement outside the range of the sheet feeder 2.The remaining-stack bars 7 are subdivided into thicker carrying bars andthinner spacing bars and are arranged in an alternating arrangement.

The remaining-stack carrying device 3 with its frame 6 is guided bymeans of the guide rails 8 on the sheet feeder 2, and it is verticallymovable. The remaining-stack lifting mechanism 5 is indicated in itsposition and is located as is generally the case on the upper side ofthe guide rails 8, for example on the frame of the sheet feeder 2, itengages from there onto the rack 6 of the remaining-stack carryingdevice 3 and moves the latter up and down on the guide rails 8.

FIG. 1 shows that the remaining-stack carrying device 3 is installeddirectly into the sheet feeder 2, by means of the guide rails 8. Theremaining-stack lifting mechanism 5, on the one hand, is movable up anddown during the supplying of the printing machine 1 with sheets, and theremaining-stack carrying device 3, on the other hand, is movable outsideof the processing zone for the stack changing proper.

The stack changing proceeds, therefore, as follows:

I. Start on reaching a limit height of the sheet stack S.

II. Remaining-stack bars 7 are thrust in common from the rack 6 into thegrooves of the pallet underneath the sheet stack S.

III. Carrying bars are undercut by a remaining-stack lifting rail andraised until the remaining-stack H is carried by the carrying bars 7.

IV. The pallet is lowered and removed from the sheet feeder 2.

V. Lifting of the remaining-stack with the remaining-stack liftingmechanism 5 to the sheet singling element.

VI. Install the new sheet stack S into the sheet feeder 2.

VII. On contact of the upper side of the sheet stack S with the carryingbars the pulling process is initiated: the carrying bars 7 are pulled inpairs from inside outward between the remaining-stack H and the sheetstack S.

VIII. The remaining-stack places itself from inside and outward upon thespacing bars.

IX. The remaining-stack lifting rail becomes free, the remaining-stackcarrying device 3 no longer takes on any load, the spacing bars controlthe stack unification.

X. Spacing bars are continuously drawn out from inside outward betweenthe remaining-stack and the sheet stack S.

XI. Remaining-stack deposits itself continuously on the sheet stack S.

In a modified version of the run-off, the following procedure isfollowed:

I. Remaining-stack carrying device 3, after pulling of thecarrying/spacing bars is immediately lowered to the stack underedge ofthe new sheet stack S.

II. The carrying/spacing bars are introduced into the grooves of thepallet, in which operation the thrusting-in path is shorter than thetotal thrusting-in path.

III. Remaining-stack carrying device 3 is raised load free,synchronously with the sheet stack S.

IV. On reaching the limit height of the sheet stack S thecarrying/spacing bars are thrust-in entirely.

V. The remaining-stack lifting rail takes over the carrying bars.

The run-off is continued as described above.

For implementing this run-off, in FIGS. 3 to 5 how the remaining-stacklifting mechanism 5 functions is schematically shown. Theremaining-stack lifting mechanism 5 has three pairs of lifting chains60, 61 and 62. The lifting chains 60 (dashed) are arranged on the frontside of the remaining-stack lifting mechanism 5 corresponding to thesheet-processing machine. On this side the remaining-stack lifting railis also coupled with the lifting chains 60. It lies, for example, in avertical guide on supporting stops (not shown here) and can be liftedfrom there by means of the remaining-stack lifting mechanism 5. Thelifting chains 61 (line double-pointed) are assigned to the oppositelylying rear side of the remaining-stack lifting mechanism 5. The liftingchains 62 (dotted-dashed) are assigned to the rack 6 of theremaining-stack carrying device 3. The lifting chains 60 and 61(dashed-double-dotted) are led over chain-deflecting wheels in the frameof the sheet feeder 1 to a remaining-stack lifting drive 63. The liftingchains 60 to 62 are led on both sides of the sheet feeder 2 overdeflecting wheels (here only indicated) in traverses 64. The traverses64 are joined in the frame of the sheet feeder 2 with theremaining-stack carrying device 3 and are guided vertically slidably onthe guide rails 8 in common with the remaining-stack carrying device 3by means of the remaining-stack lifting mechanism 5. The traverses 64have supports on their front ends on which the remaining-stack liftingrail can be led along. For this, the remaining-stack lifting rail, inthe lifting movement of the remaining-stack lifting mechanism 5 andtherewith of the traverses 64, is lifted off from its lower end positionor waiting position, and raised with the remaining-stack carrying device3. The remaining-stack lifting rail can obviously also be firmly joinedwith the traverses 64.

The ends of the lifting chains 60 and 61 are firmly joined on thetraverses 64 with a slidable bearing block 65. On the slidable bearingblock 65 there is borne a deflecting chain wheel 66. Around thedeflecting chain wheel 66 the lifting chain 62 is led in a loop. Thelifting chain 62 is further led over a deflecting chain wheel 67 fromthe traverse 64 upward to a deflecting chain wheel 68 on a support 69carried along with the remaining-stack carrying device 3, or on theupper end of the guide rail 8 and it extends from there downward again.The ends of the lifting chain 62 are firmly attached, on the one hand,to the traverse 64 and, on the other hand, to the frame 6 of theremaining-stack carrying device 3. As a consequence of the weight of theremaining-stack carrying device 3 together with the traverses 64, thelifting chain 62 is tensioned over the loop about the deflecting chainwheel 66 against the lifting chains 60 and 61 and therewith also againstthe remaining-stack lifting drive 63.

In the bottom position shown in FIG. 3, the lifting chains 60 and 61 arelargely driven out. The slidable bearing block 65, with the deflectingchain wheel 66, is fixed in this operating position by means of thechain loop, to the right against a stop. The frame 6 of theremaining-stack carrying device 3 is suspended by the lifting chains 62.The frame can also become seated, with respect to the traverses downwardon a stop. The lifting chain 62 is then tensioned over the chain loop onthe bearing block 65.

In the raising of the remaining-stack carrying device 3, as shown inFIG. 4, the lifting chains 60 and 61 are drawn in by the remaining-stacklifting drive 63. The bearing block 65 is further held over the chainloop in its right hand end position bounded by the length of the liftingchain 62. In the highest possible operating position of theremaining-stack carrying device 3 in the stack zone the traverses 64 runagainst stops, which are not shown in this case. Now a further liftingmovement of the traverses 64 together with the rack 6 is not possible.

In FIG. 5 finally there is shown the out-of-operation position of theremaining-stack carrying device 3. By further actuating of theremaining-stack lifting drive 63, over the lifting movement of thelifting chains 60 and 61, the bearing block 65 is shifted to the left onthe traverses 64. Here the lifting chain 62 runs off over the deflectingchain rolls 66, 67 and 68. The loop in the lifting chain 62 islengthened there, while the end of that lifting chain 62 that isfastened to the rack 6 is drawn in. Thereby, the frame 6 is lifted bythe traverses 64 and raised beyond the upper-end position of thetraverses 64. The frame 6 carrying the remaining-stack bars 7 of theremaining-stack carrying device 3 is thus brought into a parkedposition. In this position it is taken out of operation.

In the lowering of the rack 6 and extension of the traverses 64 the twoparts of the remaining-stack carrying device 3 join again and descend incommon under the weight load with tensioned lifting chain 62.

The remaining-stack lifting mechanism 5 also is otherwise constructedwith further details. Thus, the lifting action of the lifting chain 62can be increased or decreased by altered deflections in the area of theloop. In this case, for example, there comes in question the action of apulley block. Further, the connection both of the bearing block 65 andalso the connection of the frame 6 with the traverses 64 can be madelockable. This, however, according to experiences of hitherto, is notrequired.

The remaining-stack carrying device 3, integrated into the sheet feederwith automatic hoisting of the rack 6 carrying the remaining-stack bars7, permits the re-equipping of existing sheet feeders 2 with theequipment mentioned for the automatic stack changing. In this instance,despite extended functional possibilities, no additional constructionspace is required as is the case with other known devices.

What is claimed is:
 1. A device for changing a sheet stack in a sheetfeeder of a sheet-processing machine, the device comprising: a mainstack lifting mechanism for raising and lowering of a sheet stack, aremaining-stack carrying device including remaining-stack bars fortemporarily receiving a remaining stack and transferring said remainingstack to a newly fed-in sheet stack, a drive mechanism for slidablymoving the remaining-stackbars longitudinally into a stack position instaggered relation to one another and retracting the remaining-stackbars from the stacking position in staggered relation to one another,and a remaining-stack lifting mechanism for raising the remaining-stackcarrying device, wherein the remaining-stack carrying device includes afirst portion connected to the remaining-stack lifting mechanism and asecond portion that carries the remaining-stack bars, the first andsecond portions of the carrying device being guided on vertical guiderails mounted on the sheet feeder with the first portion of the carryingdevice being arranged inside the sheet feeder and the second portion ofthe carrying device being arranged outside of the sheet feeder.
 2. Thestack changing device according to claim 1 wherein the remaining-stacklifting mechanism has an automatic drive connection with a liftingarrangement for moving the second portion of the carrying device withrespect to the first portion of the carrying device on the verticalguide rails.
 3. The stack changing device according to claim 1 whereinthe first portion of the carrying device comprises traverses connectedwith the remaining-stack lifting mechanism and the second portion of thecarrying device comprises a rack for carrying the remaining-stack bars,the traverses and rack being guided together on the vertical guiderails.
 4. The stack changing device according to claim 3 wherein therack is vertically movable on the guide rails with respect to thetraverses by a lifting device.
 5. The stack changing device according toclaim 3 wherein the traverses include guides for a remaining-stacklifting rail which is guided vertically on the front side of the sheetfeeder, the remaining-stack lifting rail being coupleable with theguides through the lifting movement of the remaining-stack carryingdevice such that the remaining-stack lifting rail is raisable from alower end position together with the remaining-stack carrying device. 6.The stack changing device according to claim 5 wherein theremaining-stack lifting mechanism includes two pairs of lifting chains,a first drive mechanism for lifting a remaining stack, and a seconddrive mechanism for moving the rack with respect to the traverses. 7.The stack-changing device according to claim 6 wherein the rack isconnected to the traverses by leading the lifting chains over chaindeflecting rollers on the upper end of the guide rails.
 8. The stackchanging device according to claim 7 wherein the second drive mechanismincludes a bearing block which is slidably mounted on the traverses andto which each of the lifting chains of the remaining-stack liftingmechanism is connected, and a rack lifting chain which is looped arounda deflecting roller on the bearing block.
 9. The stack changing deviceaccording to claim 8 further comprising stops for limiting the upwardmovement of the traverses on the guide rails.